lang: funcs: core: iter: Add map iterator function part3

This flattens the type unification of the map function so that the
solver has more to work with. It's possible that some scenarios might
solve faster, or without recursion, after this improvement.

lang/funcs/core/iter/map_func.go

@@ -91,6 +91,21 @@ func (obj *MapFunc) Unify(expr interfaces.Expr) ([]interfaces.Invariant, error)
 	dummyArgFunc := &interfaces.ExprAny{} // corresponds to the input func
 	dummyOutList := &interfaces.ExprAny{} // corresponds to the output list
 
+	t1Expr := &interfaces.ExprAny{} // corresponds to the t1 type
+	t2Expr := &interfaces.ExprAny{} // corresponds to the t2 type
+
+	invar = &interfaces.EqualityWrapListInvariant{
+		Expr1:    dummyArgList,
+		Expr2Val: t1Expr,
+	}
+	invariants = append(invariants, invar)
+
+	invar = &interfaces.EqualityWrapListInvariant{
+		Expr1:    dummyOutList,
+		Expr2Val: t2Expr,
+	}
+	invariants = append(invariants, invar)
+
 	// full function
 	mapped := make(map[string]interfaces.Expr)
 	ordered := []string{inputsName, functionName}
@@ -105,6 +120,18 @@ func (obj *MapFunc) Unify(expr interfaces.Expr) ([]interfaces.Invariant, error)
 	}
 	invariants = append(invariants, invar)
 
+	// relationship between t1 and t2
+	argName := util.NumToAlpha(0) // XXX: does the arg name matter?
+	invar = &interfaces.EqualityWrapFuncInvariant{
+		Expr1: dummyArgFunc,
+		Expr2Map: map[string]interfaces.Expr{
+			argName: t1Expr,
+		},
+		Expr2Ord: []string{argName},
+		Expr2Out: t2Expr,
+	}
+	invariants = append(invariants, invar)
+
 	// generator function
 	fn := func(fnInvariants []interfaces.Invariant, solved map[interfaces.Expr]*types.Type) ([]interfaces.Invariant, error) {
 		for _, invariant := range fnInvariants {
@@ -127,9 +154,6 @@ func (obj *MapFunc) Unify(expr interfaces.Expr) ([]interfaces.Invariant, error)
 			var invariants []interfaces.Invariant
 			var invar interfaces.Invariant
 
-			t1Expr := &interfaces.ExprAny{} // corresponds to the t1 type
-			t2Expr := &interfaces.ExprAny{} // corresponds to the t2 type
-
 			// add the relationship to the returned value
 			invar = &interfaces.EqualityInvariant{
 				Expr1: cfavInvar.Expr,
@@ -150,6 +174,18 @@ func (obj *MapFunc) Unify(expr interfaces.Expr) ([]interfaces.Invariant, error)
 			}
 			invariants = append(invariants, invar)
 
+			invar = &interfaces.EqualityWrapListInvariant{
+				Expr1:    cfavInvar.Args[0],
+				Expr2Val: t1Expr,
+			}
+			invariants = append(invariants, invar)
+
+			invar = &interfaces.EqualityWrapListInvariant{
+				Expr1:    cfavInvar.Expr,
+				Expr2Val: t2Expr,
+			}
+			invariants = append(invariants, invar)
+
 			var t1, t2 *types.Type                       // as seen in our sig's
 			var foundArgName string = util.NumToAlpha(0) // XXX: is this a hack?
 
@@ -264,34 +300,22 @@ func (obj *MapFunc) Unify(expr interfaces.Expr) ([]interfaces.Invariant, error)
 					Type: t1,
 				}
 				invariants = append(invariants, invar)
-
-				invar = &interfaces.EqualityWrapListInvariant{
-					Expr1:    cfavInvar.Args[0],
-					Expr2Val: t1Expr,
-				}
-				invariants = append(invariants, invar)
-				// we already have the mapping, but add both in
-				// case we need to solve these from either side
-				invar = &interfaces.EqualityWrapListInvariant{
-					Expr1:    dummyArgList,
-					Expr2Val: t1Expr,
-				}
-				invariants = append(invariants, invar)
 			}
 
 			if t1 != nil && t2 != nil {
-				argName := foundArgName // XXX: is this a hack?
-				mapped := make(map[string]interfaces.Expr)
-				ordered := []string{argName}
-				mapped[argName] = t1Expr
-
-				invar = &interfaces.EqualityWrapFuncInvariant{
-					Expr1:    dummyArgFunc,
-					Expr2Map: mapped,
-					Expr2Ord: ordered,
-					Expr2Out: t2Expr,
-				}
-				invariants = append(invariants, invar)
+				// TODO: if the argName matters, do it here...
+				_ = foundArgName
+				//argName := foundArgName // XXX: is this a hack?
+				//mapped := make(map[string]interfaces.Expr)
+				//ordered := []string{argName}
+				//mapped[argName] = t1Expr
+				//invar = &interfaces.EqualityWrapFuncInvariant{
+				//	Expr1:    dummyArgFunc,
+				//	Expr2Map: mapped,
+				//	Expr2Ord: ordered,
+				//	Expr2Out: t2Expr,
+				//}
+				//invariants = append(invariants, invar)
 			}
 
 			// note, currently, we can't learn t2 without t1
@@ -301,19 +325,6 @@ func (obj *MapFunc) Unify(expr interfaces.Expr) ([]interfaces.Invariant, error)
 					Type: t2,
 				}
 				invariants = append(invariants, invar)
-
-				invar = &interfaces.EqualityWrapListInvariant{
-					Expr1:    dummyOutList,
-					Expr2Val: t2Expr,
-				}
-				invariants = append(invariants, invar)
-				// we already have the mapping, but add both in
-				// case we need to solve these from either side
-				invar = &interfaces.EqualityWrapListInvariant{
-					Expr1:    cfavInvar.Expr,
-					Expr2Val: t2Expr,
-				}
-				invariants = append(invariants, invar)
 			}
 
 			// We need to require this knowledge to continue!